With no disrespect to our fellow data scientists over "the pond", one major problem from the rest of the world's point of view with questions like Publicly Available Datasets is the American focus of the answers. They are great answers, and great sources of data, but lack a lot relevance to others not in the US due to geographic, demographic, social or other factors.

This question I have is particularly focused on public data sites for the UK.

Are there sites that have a large variety of data collected? I suspect at the moment the UK isn't as progressive as the USA in terms of meta-data repositories, so I would be happy for sites that are quite rich in content and interesting in terms of their data science or analytical possibilities!

The Health and Social Care Information Centre (soon to be renamed NHS Digital) which make a wide range of health-related data available on various terms. data can sometimes be hard to find but there is a lot there including vast quantities of data about England's NHS (e.g. everything prescribed by each GP practice every month, vast quantities of different indicators about health outcomes and population health).

The Land Registry. They have a dataset of all property transactions since about 1995 (i.e. the record of prices paid for domestic housing) which is fascinating.